The demand for energy conservation has grown substantially due to concerns over limited resources and the environment. This has led to advances in energy efficient appliances. Heat transfer systems generally operate to transfer heat from an area of higher temperature to an area of lower temperature. In some cases, this can act as a refrigerator to remove heat from a chamber and deposit the heat in an environment external to the chamber. In other cases, a heat transfer system can be used to condition the air in a chamber such as a room or a house. In these cases, the heat transfer system may operate to remove heat from the chamber (cooling) or deposit heat in the chamber (heating).
The most common type of energy efficient heat transfer systems use vapor compression systems. In these systems, mechanical components consume energy to actively transport heat. These components may include a compressor, a condenser, a thermal expansion valve, an evaporator, and plumbing that circulates a working fluid (e.g., refrigerant). The components circulate the refrigerant, which undergoes forced phase changes to transport heat to/from a chamber from/to an external environment.
However, vapor compression systems are designed with a capacity that matches the maximum amount of heat transfer that may be needed. Therefore, in most situations, the vapor compression system is overpowered and must be cycled on and off (e.g., a duty cycle) to maintain the proper amount of heat transfer or to maintain a set point temperature range of a chamber. While the vapor compression system may be efficient when on, it may lead to heat leak back and other negative results when the vapor compression system is off. As such, systems and methods are needed for heat transfer that provides higher energy efficiency at lower costs while maintaining versatility of performance.